1. Technical Field
The present invention relates to a liquid jet head for ejecting and recording droplets on a recording medium, a liquid jet apparatus, and a method of manufacturing the liquid jet head.
2. Related Art
In recent years, there has been utilized an ink jet type liquid jet head for ejecting droplets, such as ink, on a recording paper or the like and recording characters or graphics, or an ink jet type liquid jet head for ejecting a liquid material on a surface of an element substrate and forming a functional thin film. In this system, ink or a liquid material (hereinafter, referred to as “liquid”) is guided to a channel from a liquid tank via a supply tube, a pressure is applied to the liquid filling the channel, and the liquid is ejected from a nozzle communicated with the channel. When the liquid is ejected, the liquid jet head or the recording medium is moved and characters or graphics are recorded, or a functional thin film having a predetermined configuration is formed.
FIG. 20 is a schematic partial cross-sectional view (FIG. 3 in JP 2009-532237 W) of an ink jet head 100 which is a liquid jet head of this type. The ink jet head 100 has a laminate structure including a nozzle plate 124, a cover member 126, a piezoelectric member 128, and a base material 136. A pair of nozzles 130 is formed on the nozzle plate 124, which is an uppermost layer. A straightedge-shaped opening 129 corresponding to each of the nozzles 130 is formed at the cover member 126, which is a layer under the nozzle plate 124. The pair of piezoelectric members 128 formed by two trapezoidal walls and a frame member 138 which is on the outside thereof are provided between the cover member 126 and the base material 136. A manifold 132 for introducing liquid and a manifold 134 for discharging the liquid are formed at the base material 136. The plurality of piezoelectric members 128 as trapezoidal walls is arrayed separately in a direction vertical to the paper surface, and a channel is formed between the two piezoelectric members 128 arrayed in the direction vertical to the paper surface. Accordingly, the ink jet head 100 is provided with a plurality of paired two channels formed in parallel in the direction vertical to the paper surface.
FIG. 21 is a perspective view of the ink jet head 100, from which the above-described nozzle plate 124 and cover member 126 have been removed (FIG. 4 in JP 2009-532237 W). The manifold 132 for introducing the liquid and the manifold 134 for discharging the liquid are formed at the base material 136, which is a lower layer. The piezoelectric members 128, which are trapezoidal walls, are provided between the manifolds 132, 134 in parallel in two rows and a periphery thereof is surrounded by the frame member 138. Accordingly, the ink jet head 100 has a structure in which the liquid introduced through the manifold 132 flows in the channel between the trapezoidal walls formed by the piezoelectric members 128, is discharged through the manifolds 134 on both sides, and does not flow to the outside of the frame member 138. A drive electrode (not illustrated) is formed on each side surface of the trapezoidal piezoelectric member 128. When a voltage is applied to the drive electrodes on these side surfaces, the piezoelectric member 128 is deformed in a shear mode, generating a pressure wave in the liquid in the channel. Droplets are ejected from the nozzle 130 by this pressure wave.
Here, a plurality of wiring electrodes is formed on a surface of the base material 136 on the channel side. One end of the wiring electrode is connected to the drive electrode on the side surface of the piezoelectric member 128 and another end thereof is connected to an electrode terminal or a driver IC, which is provided outside an outer periphery of the frame member 138. Consequently, a drive signal for driving the piezoelectric member 128 is supplied from the nozzle plate 124 side of the base material 136. It should be noted that JP 2009-532237 W describes an example in which the cover member 126 illustrated in FIG. 20 can be removed and the nozzle plate 124 is directly provided on a top surface of the piezoelectric member 128, which is a movable wall.
FIG. 22 is a schematic cross-sectional view of another liquid jet head 101 (FIG. 4 in JP 2011-104791 A). The liquid jet head 101 has a laminate structure including a nozzle plate 102, a piezoelectric plate 104, a cover plate 108, and a flow path member 111. Liquid is ejected from a pair of nozzles 103a, 103b. A deep groove 105a and a shallow groove 105b are alternately formed at the piezoelectric plate 104 in a direction vertical to the paper surface. The deep groove 105a has a depth reaching the nozzle plate 102 and communicates with the pair of nozzles 103a, 103b. The shallow groove 105b has a depth not reaching the nozzle plate 102. The deep groove 105a and the shallow groove 105b of the piezoelectric plate 104 are partitioned by a wall formed by the piezoelectric plate 104, and a drive electrode (not illustrated) is formed on each side surface of the wall. Liquid supplied from a supply joint 114 flows into the deep groove 105a via a liquid supply chamber 112 and a liquid supply port 109, flows out to a pair of liquid discharge ports 110a, 110b, and is discharged from a pair of liquid discharge chambers 113a, 113b and discharge joints 115a, 115b. Meanwhile, since an upper opening of the shallow groove 105b is blocked by the cover plate 108, the liquid does not flow therein.
By applying a drive signal to the drive electrodes on the wall partitioning the deep groove 105a and the shallow groove 105b, the wall is deformed in a thickness-shear mode, generating a pressure wave in the liquid filling the deep groove 105a. As a result, droplets are ejected from the nozzles 103a, 103b. Wiring electrodes (not illustrated) are formed on a surface of the piezoelectric plate 104 on the cover plate 108 side. One end of the wiring electrode is connected to the drive electrode formed on the wall and another end thereof is connected to an electrode terminal formed on a surface of the cover plate 108 side. The electrode terminal is connected to a drive circuit via a flexible substrate or the like.